New research indicates that racial attitudes toward African-Americans have worsened since the election of President Barack Obama.

Many people described America as accepting of all races after Obama was voted as the country's first black president in 2008. However, a new poll shows that anti-black sentiments became more common in the last four years.

Since 2008, explicit racism was more common among Republicans than Democrats. In 2012, the proportion of people expressing anti-black attitudes was 79 percent among Republicans, 48 percent among independents and 32 percent among Democrats.If the findings hold during next week's presidential elections, Obama's race may play a factor in voters' choices.

The study's authors include Josh Pasek, assistant professor of communication studies at the University of Michigan; Jon Krosnick, professor of communication and political science at Stanford University; and Trevor Tompson, director of the Associated Press-NORC Center for Public Affairs Research at the University of Chicago.

"It appears that the Obama administration has not been a time of decline in anti-black attitudes in America," the researchers wrote. "Indeed, these data suggest that anti-black attitudes have become slightly more prevalent over those years, especially during the last two years."

Using data from surveys done in 2008, 2010 and 2012, the researchers found that:

Sizable proportions of both Democrats and Republicans manifested anti-black attitudes, though anti-black attitudes were more common among Republicans than among Democrats.

People who identified themselves as Republicans in 2012 expressed anti-black attitudes more often than did Republican identifiers in 2008.

People with more negative attitudes toward African-Americans were less likely to approve of Obama's job performance.

If both anti-black and pro-black attitudes had been converted to be neutral, the proportion of Americans disapproving of Obama's job performance would have been 1 to 3 percentage points lower in both 2010 and 2012.

In 2012, holding negative attitudes toward African-Americans increased the likelihood of voting for Republican presidential candidate Mitt Romney and not voting at all, and decreased the likelihood of voting for Obama.

When testing for implicit attitudes, the scores for anti-black sentiment increased from 49.3 percent in 2008 to 51.1 percent in 2010 and 55.7 percent in 2012.

Overall, the expected influence of anti-black attitudes on the election mirrored what we found in a similar examination in 2008, Pasek said.

"In an election projected to be this close, the two-point margin we attribute to prejudice may play a critical role in determining our next president," he said.